Carbon aerogel spheres were activated by carbon dioxide (CO

2

) and potassium hydroxide (KOH)

respectively. The electrodes of supercapacitor were made from the products before and after activation. To understand the activation mechanism

the pore structure and electrochemical performance of these products were investigated. The results showed that both CO

2

and KOH activation could improved the pore structure and electrochemical performance

the highest BET surface area of active products could reach 1 320 m2/g and the capacitance were increased by three times

respectively. Furthermore the results also showed that the activation mechanisms of  CO

2

and KOH were different. The mesopores of carbon aerogel spheres were kept after CO

2

activation. Such mesopores acted as the fast channel of electrons to enhance mass transfer rate. The micropores of carbon aerogel spheres were increased significantly after KOH activation

which enhanced the active surface area to improve the electrochemical performance.